This invention is directed generally to the antenna cuts, and more particularly radiating elements for antennas.
Many wireless and broadcast applications require transmission and/or reception on orthogonal linear polarizations. This may be done for a variety of reasons. In some applications, transmission is done with one polarization and reception is done with the orthogonal polarization in order to provide isolation between the transmitted and received signals. In other cases energy is received on both polarizations and the signals are combined by a method that increases the signal/noise ratio, providing polarization diversity gain. In order to implement these schemes effectively, it is necessary that a relatively high level of isolation exist between the two polarizations. For array antenna applications, aesthetic and environmental requirements make it desirable for the two polarizations to be emitted from a single multi-component radiating structure.
There are several types of radiating structures that provide for highly-isolated orthogonal radiation within a compact structure. One is a square patch, which can be made to radiate from orthogonal edges. Another is a pair of dipoles, arranged orthogonally and crossing at their midpoints. A third method involves arranging four dipoles so that each dipole defines one side of a square which has a side length larger than the length of the dipoles so that the edges or tips of the dipoles do not touch at the corners of the square. Each polarization is emitted by one of the two pairs of parallel dipoles thus defined, which are fed so as to radiate with equal amplitude and phase.
A given dipole couples strongly, typically at levels of xe2x88x929 to xe2x88x9212 dB, with the neighboring orthogonal dipoles. However, if the two parallel neighboring dipoles are fed with equal phase and amplitude and are arranged symmetrically with respect to the orthogonal dipole(s), then the coupled energy from one neighboring dipole will be of equal magnitude and opposite phase as energy from the other neighboring dipole. The two coupled fields therefore cancel out. In practice, coupling levels of less than xe2x88x9230 dB may be achieved.
Accordingly, it is a general object of the invention to provide a dual-polarized radiating element with high isolation between polarization channels and a method of wireless communications utilizing such a radiation element.
Briefly, in accordance with the foregoing, a radiating element for use in a dual-polarized radiating apparatus with isolation between polarization channels comprises a dielectric body having one or more conductive radiators thereon, said dielectric body having oppositely outwardly extending lateral side portions which extend beyond lateral outer edges of said conductive radiators, and cooperating joining structure for interengaging an edge of said dielectric body with an adjacent edge of a similar dielectric body to form at least a portion of said dual polarized radiating apparatus.